英语阅读。急求答案。（2-1）

The air surrounding us is important to everyone. Without air, we could not exist. Everyone understands that. But air is necessary in many other ways—ways that are not always so obvious or widely known.
For example, if we did not have air, there would be no sound. Sound travels through air. Where there is no air, there is no sound. Without air, there would be no fire. There would be no automobiles, since motors need air in order to operate.
Without air, there would be no wind or clouds. There would be no weather, as we know it. The night time would be very cold and the days very hot. We would be forced to seek shelter from the sun, as there would be no atmosphere to protect us from the sun’s deadly rays.
The atmosphere is all the air surrounding the earth. Atmospheric pressure is the weight of all that air against the surface of the earth. If we did not have atmospheric pressure, we could not have automobile tires. The tires would swell or burst if they did not have the pressure of the atmosphere against their surfaces.
Large and powerful, the atmosphere consists of an ocean of gases hundreds of miles high. It presses down on our bodies with a force of more than fourteen pounds per square inch. The narrow column of air which rests upon our shoulders weighs almost 2,000 pounds. But our bodies are built in such a way that its weight does not crush us.
In this huge ocean of air there is more energy than in all the coal, oil, and gas we have on earth. Electrical energy is collected in the atmosphere as water is collected and stored in a dam. The existence of electricity in the air has been known for centuries. Men have gazed in wonder at the bright patterns of lightning in storm clouds. But a thorough study of electricity in the atmosphere was not possible until the development of radio and radar.
One scientist, Dr. Sydney Chapman, has tried to explain the electric field which surrounds the earth. He believes that the great storms on the sun create large amounts of electric energy. This energy is contained in a very light gas called hydrogen. The earth pulls the gas toward it, and a ring is formed around the earth several thousand feet above its surface. The great space ring is a powerful current of electrical energy. Sometimes the ring comes down and curves into the lower atmosphere, causing strange electrical effects.
Dr. Chapman’s ideas explain many things. It has long been known that there is an electric field inside the earth. It moves in much the same manner as the electric energy contained in the atmosphere. Scientists now believe that the electric energy in the atmosphere causes the electric energy inside the earth to flow.

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